Compare the string with some numeric equivalent

Question

Can you tell me the input so that the check statement is passed along with the try..except of the input pin

#!/usr/bin/python
# Secure Pin system
import sys

users = {'admin': '<REDACTED>'}

def register(username, password):
    if username in users:
            return "User already exits."
    users[username] = password
    return "Registered Successfully."        

def login(username, password):
    if username not in users:
            return "Wrong pin/password"
    if password != users[username]:
            return "Wrong pin/password"
    if username == "admin":
            return "The FLAG is what you entered in the \"Pin\" field to get here!"
    return "You must login as admin to get the flag"

def handle_command(command):
    if command not in ["REG", "LOGIN"]:
            return "Invalid Command!"
    print "Username:",
    sys.stdout.flush()
    username = raw_input()

    try:
            print "Pin ([0-9]+):",
            sys.stdout.flush()
            password = input() # we only support numbers in password

    except:
            return "Please enter a valid password. Pin can only contain digits."        
    if command == 'REG':
            return register(username, password)
    if command == 'LOGIN':
            return login(username, password)

if __name__=="__main__":
    print "Hey welcome to the admin panel"                
    print "Commands: REG, LOGIN"
    try:
            print ">",
            sys.stdout.flush()
            command = raw_input()
            print handle_command(command)
            sys.stdout.flush()
    except:
            pass

The code is all right but the only thing is to bypass the input check There is a bug that is to be identified

Answer 1

If you want to check whether the input from user only has numbers, then you can use the method - str.isnumeric() , to check whether the string only contains numbers.

Example -

>>> "123".isnumeric()
True
>>> "123.21".isnumeric()
False
>>> "abcd".isnumeric()
False

You can do this check instead of a try/except block (since you do not really use the password as a number after this block).

Answer 2

To ensure the user enters a number, you could convert the script to use a function as follows:

def get_input_number(prompt):
    while True:
        try:
            user_num = int(raw_input(prompt))
            return user_num
        except ValueError:
            print "Please enter a valid password. Pin can only contain digits."

password = get_input_number("Pin ([0-9]+): ")

This would then keep prompting until a number is entered.